The present invention relates to a coaxial connector with locking by snap-fastening.
European patent application EP 1 094 565 describes a coaxial connector comprising a connector element and a complementary connector element. The connector element has a sleeve carrying snap-fastening tabs whose free ends present respective shoulders suitable for coming into abutment against a sloping surface of the complementary connector element in such a manner as to exert an axial force thereon. That connector is satisfactory in terms of leakage at microwave frequencies, but relatively high levels of interfering frequencies appear in that connector due to the phenomenon of intermodulation, and that is unacceptable, particularly in the field of telecommunications where microwave signals are being transmitted to an antenna or from an antenna.
There exists a need for coaxial connectors that present a high level of shielding against leakage in the microwave range, simultaneously with good characteristics concerning intermodulation, in particular for frequencies lying in the range 1 gigahertz (GHz) to 6 GHz approximately.
The invention satisfies this need by means of a coaxial connector with locking by snap-fastening, the connector comprising two complementary connector elements each comprising a tubular body forming a ground contact and containing a central contact, which central contact is male in one of the bodies and female in the other and is held in the corresponding body by means of insulation, wherein a first one of the connector elements has a retaining member suitable for exerting a radial force on the second connector element which is arranged in such a manner that said radial force generates an axial force on the second connector element tending to press it axially against a bearing surface of the first connector element, and wherein the body of one of the connector elements has a member inserted therein that forms an internal ground contact and that is suitable for coming into contact with an inner wall of the body of the other connector element while exerting relatively strong contact pressure thereagainst.
By means of the invention, the contact made between the internal ground contact forming member and the above-mentioned inside wall ensures electrical continuity between the two ground contact forming bodies while allowing relatively strong contact pressure to apply in the contact zones. Said internal ground contact forming member enables the major fraction of the current to be conveyed which, at high frequencies, flows in a skin thickness facing the central contact. This significantly reduces the interfering frequencies generated by the intermodulation phenomenon.
Furthermore, the electrical contact between the two connector elements obtained by means of the above-mentioned axial thrust serves to convey the residual currents generated by the leaks through the internal ground contact forming member. Since these residual currents are relatively weak and since the intermodulation phenomenon is essentially non-linear in nature, occurring only at high levels of current, this current gives rise only to low levels of interfering frequencies due to the intermodulation phenomenon. This contact also makes it possible to reduce significantly the level of leakage at microwave frequencies.
The connector of the invention thus presents shielding characteristics that are entirely satisfactory together with a low level of intermodulation.
Finally, the invention enables the elements of the connector to be assembled together easily, which assembly can be implemented essentially by snap-fastening.
Preferably, the second connector element has a front end that bears against the bearing surface of the first connector element.
In a preferred embodiment of the invention, the internal ground contact forming member is inserted by force in said first contact element.
Advantageously, the internal ground contact forming member has a plurality of elastically deformable tabs suitable for bearing against the above-mentioned inner wall.
Preferably, the second connector element has a generally frustoconical bearing surface against which the retaining member can come to bear so that the radial force exerted thereby generates an axial force on the second element.
Said generally frustoconical surface may be formed in an annular groove of the body of the second connector element.
In an embodiment of the invention, the retaining member is constituted by a generally frustoconical split ring that presents radial elasticity.
The axial end of the split ring presenting the smaller cross-section may have a rim that is directed radially outwards.
In another embodiment of the invention, the retaining member has elastically deformable tabs with free ends that together define an annular bead suitable for coming to bear against said generally frustoconical surface.
In which case, the retaining member also forms an external ground contact.
The front end of the second connector element may come directly into contact with a wall made on the body of the first connector element.
In a variant, said first connector element includes an axially-compressible gasket made in particular out of an elastomer filled with a conductive metal, the front end of the second connector element coming to bear against said gasket.
The gasket may be housed in an annular groove of the internal ground contact forming member.
Because of the compressibility of the gasket, it is possible to make some of component parts of the connector using dimensional tolerances that are slacker.
In a variant, the connector includes a contact washer interposed between the front end of the second connector element and a wall of the first connector element, said washer being suitable for being compressed axially.
The washer may present an undulating profile, or in a variant it may be generally frustoconical in shape.
The washer may be made of an elastic metal material, for example.